New grounding questions

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  #1  
Old 04-30-01, 02:26 PM
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Hi,

OK, as I understand household grounding, the equipment ground (green/bare, 3rd wire, etc.) serves the safety purpose of providing an alternate current path in the event of a ground fault. In two wire systems, GFCI provide equivalent protection through a different means--by tripping when there is a difference in current between the hot and neutral...indicating a current leakage (something or someone is providing an alternate path back to the transformer.

So far so good?

But here are some questions:

1) Why does the NEC no longer allow ground wires to be run to the nearest cold water pipe? Why do they have to run back to the service entrance? Should existing grounds be changed to conform?

2) I read that, even in a GFCI protected two wire system, computers and electronics need to be on a grounded, three wire circuit. Why?

3) Related to the question above...is it true that surge protectors are not effective unless the circuit has a ground wire? Or does this differ with different surge protector designs? Or does it provide some protection, but under more limited circumstances?

Thanks for your advice.
 
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  #2  
Old 04-30-01, 02:59 PM
Gary Tait
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1: So you don't light up the plumbing.

2: Computers need a real ground for surge supression,
and EMF/RFI supression.

3: Good surge supressors will sink the surge to ground.
Cheaper ones will do a hot to neutral only protection,
but is not a whole lot of good.
 
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